1. Field of the Invention
This invention relates to an apparatus for cutting large diameter pipes.
2. Description of the Prior Art
There are devices available that can cut large diameter pipe while positioned within the inside of such a pipe. However, these devices ae cumbersome and difficult to use, if not impossible to use, on spiral pipes or to make miter cuts.
U.S. Pat. No. 3,711,076 to Goetz discloses a pipe cutting machine mounted within the inside diameter of a pipe and designed to make straight cuts rather than miter cuts. The device includes a single hub to which is attached a plurality of adjusting arms for mounting the device within the pipe. A drive unit is rotatably mounted on the axis of the hub and is driven by a motor. A support unit for a cutting torch is mounted on the same axis as the drive unit, but is positioned on the opposite side of the hub with respect to the drive unit. The cutting torch includes a removable cutting torch head having a rack for adjusting the torch cutting head in relation to its distance from the wall of the pipe. The apparatus disclosed by Goetz is positioned within the pipe by adjusting telescoping legs. Such a requirement presents set-up problems, for instance, the apparatus is not self-centering. Thus, it leads to inaccuracies in alignment of the torch cutting head relative to the inside surface of large diameter pipe. The apparatus also suffers from the disadvantage that an operator must manually change the radial position of the torch head during the cutting operation if the inside diameter of the pipe is irregular. When an operator is distracted, the revolving torch may hit the inside diameter of the pipe, jamming the cutting head, or worse, damaging it. The cutter is also prone to inaccuracy when cutting pipe.
U.S. Pat. No. 2,622,327 to Halonen also relates to a rotating torch cutting apparatus for large diameter pipe. This device includes a base member having longitudinally spaced supports, wherein one of the supports rotates with the base member while the second support remains stationary. The base member has telescoping legs for supporting the device within large diameter pipe. However, the disadvantage of this device is that cables are used to control the angle of cut of the cutting assembly or cutting head and an additional cable is used to return the cutting head to an initial position. Such cables complicate operation of the device and require an operator to ensure that the cables are not tangled within the rotating mechanism. Additionally, although the cutting head can make a cut of 360.degree., the head cannot continue cutting in the same direction as the previous cut until the head is rewound to its starting position. These advantages result in a device that is imprecise, that cuts miters in a manner different from the present invention and has difficulty in cutting spiral pipe.
The present invention is directed to a pipe cutter which overcomes disadvantges of the prior art. It precisely cuts miters in a continuous manner, regardless of the type of pipe being cut. The present device is self-centering and has a minimum of moving parts. These features make this invention distinctive and novel over prior art pipe cutters.